A new genus for the Central American crab Pinnixa costaricana Wicksten, 1982 (Crustacea: Brachyura: Pinnotheridae)

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1 15 April 1997 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 110(1 ): A new genus for the Central American crab Pinnixa costaricana Wicksten, 1982 (Crustacea: Brachyura: Pinnotheridae) Ernesto Campos and Mary K. Wicksten (EC) Facultad de Ciencias, Universidad Autonoma de Baja California, Apartado Postal 2300, Ensenada, Baja California 22800, Mexico (MKW) Department of Biology, Texas A&M University, College Station, Texas Abstract. A new monotypic genus, Glassella, is recognized from the tropical East Pacific for Pinnixa costaricana Wicksten, This genus shares with Alarconia Glassell, 1938, Indopinnixa Manning & Morton, 1987, Scleroplax Rathbun, 1893 and Pinnixa White, 1846, a carapace wider than long, and third pair of walking legs the longest. Glassella is distinguished from other genera by: MXP3 with ischium-merus pyriform, carpus larger than the conical propodus, and small digitiform dactylus inserted sub-distally on the inner face of propodus. The type species is redescribed and illustrated. Pinnixa costaricana was originally described by Wicksten (1982) and placed in the genus Pinnixa White, 1846, because of its carapace shape and relative length and shape of the walking legs. During a recent revision of the Pinnixa-covcvpXcx from the eastern Pacific, P. costaricana was compared to other Pinnixa species and to species of other genera in the Pinnotheridae with a Pinnixa-Vikc morphology: Alarconia Glassell, 1938, Indopinnixa Manning & Morton, 1987, and Scleroplax Rathbun, We concluded that P. costaricana should be removed from the genus Pinnixa and placed in a new genus herein diagnosed. The morphological analysis of P. costaricana was based upon the study of the female holotype (AHF 806) deposited in Los Angeles County Museum of Natural History. Other species studied were: the type species of Alarconia, A. seaholmi, the type species of Scleroplax, S. granulata, and the species of Pinnixa reported by Bonfil et al. (1992), Zmarzly (1992), Martin & Zmarzly (1994), and Hendrickx (1995), all deposited in the San Diego Natural History Museum and at the Invertebrates Laboratory, Facultad de Ciencias, Universidad Autonoma de Baja California. The information used on the type species of Indopinnixa, I. sipunculana, was obtained from published description and figures, although critical features were confirmed by Dr. Raymond B. Manning from types deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM). Comparison of these genera is provided in a dichotomous key based on adult characters. The third maxilliped is abbreviated to MXP3 and the walking legs are indicated as WL1-WL4. AHF is an acronym for Allan Hancock Foundation. Family Pinnotheridae Glassella, new genus (Figs. 1, 2) Diagnosis. Carapace suboblong, dorsal surface pockmarked, wider than long, integument firm, regions not defined; cardiac ridge lacking; front truncated, with shallow median sulcus. MXP3 with ischium-merus pyriform, fused, separated by faint line and distal margin truncated; palp as long as ischium-merus, 3-segmented, dactylus small.

2 70 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON pockmarked, relative length 3 > 2 > 1 > 4, WL3 considerably the longest. Abdomen of female with 6 somites and telson free, widest at third somite; tapering from fourth somite to triangular telson. Male unknown. Etymology. Named in honor of Steve A. Glassell, who studied the pinnotherid crabs of the eastern Pacific and made invaluable contributions on this group. Gender feminine. Type species. Pinnixa costaricana Wicksten, 1982, by present designation and monotypy. Fig. L Glassella costaricana (Wicksten, 1982), holotype AHF 806. Dorsal view. Carapace length 1.8 mm, width 4.2 mm. digitiform, inserted sub-distally on inner face of conical propodus; carpus stout, longer than combined length of propodus and dactylus; exopod with median lobe on outer margin, flagellum 2-segmented. WLl-4 Glassella costaricana (Wicksten, 1982), new combination (Figs. 1, 2) Pinnixa costaricana Wicksten, 1982: fig. 1, 2A-D; Hendrickx, 1995:148. Material examined. Female (holotype AHF 806). Redescription. (Modified from Wicksten 1982). Carapace suboblong, cylindrical, dorsal surface pockmarked, regions not defined; anterolateral margins diverging posteriorly, forming shoulders from which side walls drop vertically; lacking anterolateral crest or cardiac ridge. Posterior margin straight. Front not advanced, truncate; with shallow median sulcus. Carapace margin with setae, especially on ventral surface. Orbits small, slightly inclined downward, filled by eyes when retracted. Antennule plicate in small fossettes. Antenna large, multi-articulated. Cheliped slender, setose. Margins of chela subparallel; ventral margin of propodus with small tubercles. Manus with group and lines of tiny tubercules. Fingers slender; tips pointed, curved, and leaving no gape when closed; dorsal margin of dactylus with blunt and acute tubercles. WLl-2 slender; meri trigonal; dactyli sharp, nearly straight. WLl twisted, somewhat smaller than second, nearly reaching end of propodus of WL2. WL2 reaching carpus of WL3. WL3 very wide; merus

3 VOLUME 110, NUMBER 1 71 D Fig. 2. Glassella costaricana (Wicksten, 1982), holotype AHF 806. A, third maxilliped (inner view); B, female abdomen; C, left chela (outer view); D, front, anterior view. 1.25X as long as wide, with stout tooth and small teeth and tubercles on ventral margin; carpus without teeth; propodus 1.5X as long as wide, with granules along flexor margin; dactyl sharp, slightly curved. WL4 short, reaching almost to end of WL3; dactyl stout, and triangular. All legs pilose and pockxnarked. Distribution and habitat. Known only from the type locality, Playa de Coco, Provincia de Guanacaste, Costa Rica (about 10 5'N, 85 45'W); low intertidal zone, sand and rock. Remarks. As noted in the key given below, the genus Glassella most resembles Pinnixa, Alarconia, Indopinnixa and Scleroplax, all of which have a firm carapace that is wider than long and a third pair of WL considerably longer than the rest. Differences among these genera include: shape, degree of development of regions and hardness of the carapace; shape, degree of fusion, articulation point and relative length of the MXP3 articles; relative length of WL; and, width and degree of fusion of the abdominal somites. Glassella costaricana can be distinguished from all other pinnotherids by the following presumed autapomorphies: MXP3 with pyriform ischium-merus;

4 72 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON shape, relative length and insertion point of the articles of the palp; and shape of the abdomen. Key to Pinnixa-like genera of the world (Carapace wider than long, firm or hard; third pair of walking legs longest.) 1. Palp of MXP3 with dactylus shorter than and inserted sub-distally on inner face of propodus; carpus larger than propodus Glassella, new genus (Pacific coast of Costa Rica; type species Pinnixa costaricana Wicksten, 1982; host unknown). - Palp of MXP3 with dactylus as long as or longer than and inserted proximally on ventral margin of propodus; carpus shorter than propodus 2 2. Ischium and merus of MXP3 not fused, subequal in length; carapace regions well defined; gonopods protruding from sternal trench and reaching to buccal cavity Alarconia Glassell, 1938 (Mexican Pacific; type species Alarconia seaholmi Glassell, 1938; host unknown). - Ischium shorter than merus or both articles fused; carapace regions not well defined, gonopods not protruding from sternal trench and not reaching the buccal cavity 3 3. Carapace subpentagonal, hard, dorsally very convex; WLl-4 of similar shape, third pair slightly longer, fourth not noticeably reduced... Scleroplax Rathbun, 1893 (Eastern Pacific, British Columbia, Canada to Baja California, Mexico; type species Scleroplax granulata Rathbun, 1893; hosts: in burrows of Crustacea-Decapoda (Callianassidae) and Echiurida. - Carapace oblong, firm but not hard, flat or slightly convex; WLl-4 very dissimilar in shape, third pair stout and longer, and fourth noticeably shorter 4 4. Propodus of MXP3 elongated, distal end expanded far beyond mid-length of dactylus, both articles of similar shape; male abdomen of 6 free somites and telson Pinnixa White, 1846 (Western Atlantic [Massachusetts, U.S.A. to Argentina]; Eastern Pacific [Alaska, U.S.A. to Chile]; Indo West Pacific [Japan, East Africa]; type species Pinnotheres cylindricum Say, 1818; host: Polychaeta, Enteropneusta, Echiurida, Sipunculida, Holothuroidea, Mollusca-Bivalvia, Crustacea-Decapoda [Callianassidae], Tunicata). - Propodus of MXP3 short and stout, distal end not reaching far beyond middle length of dactylus, both articles very dissimilar in shape; male abdomen with fifth and sixth somites fused... Indopinnixa Manning & Morton, 1987 (Indo West Pacific [Hong Kong]; type species Indopinnixa sipunculana Manning & Morton, 1987; in burrows of Sipunculida). Acknowledgments We are deeply grateful to Raymond B. Manning (USNM) for provide valuable information on Indopinnixa sipunculana; to R. B. Manning, Rafael Lemaitre and Marcos Tavares for reviewing our manuscript with great care; to Joel W. Martin and George E. Davis (LACMNH) for the loan of the holotype of Glassella costaricana; and to Alma Rosa de Campos for her very fine artistic work. This work was partially supported by program 0134 "Crustaceos Simbiontes del Pacifico Mexican (formerly de Baja California)" of the Facultad de Ciencias, Universidad Autonoma de Baja California (UABC) and by agreement UABC-CONACyT 3587-N9311. EC is a fellow of the "Programa de Estimulo al Personal Academico 96/97" of the UABC. Literature Cited Bonfil, R., A. Carvacho, & E. Campos Los cangrejos de la Bahia de Todos Santos, Baja California. Parte II. Grapsidae, Pinnotheridae y Ocypodidae (Crustacea; Decapoda: Brachyura). Ciencias Marinas (Mexico) 18(3): Glassell, S. A New and obscure decapod Crustacea from the west American coasts. Transactions of the San Diego Society of Natural History 8(33): Hendrickx, M. E Checklist of brachyuran crabs (Crustacea: Decapoda) from the eastern tropical Pacific. Bulletin de LTnstitut Royal des Sciences Naturelles de Belgique (Biologic) 65:

5 VOLUME 110, NUMBER 1 73 Manning, R. B., & B. Morton Pinnotherids (Crustacea: Decapoda) and Leptonaceans (Mollusca: Bivalvia) associated with sipunculan worms in Hong Kong. Proceedings of the Biological Society of Washington 100: Martin, J., & D. L. Zmarzly Pinnixa scamit, a new species of Pinnotherid crab (Decapoda: Brachyura) from the continental slope off California. Proceedings of the Biological Society of Washington 107: Rathbun. M. J Scientific results of explorations by the U.S. Fish commission steamer Albatross, XXIV. Description of new genera and species of crabs from the west coast of North America and the Sandwich Islands. Proceedings of the United States National Museum 16: Say, T An account of the Crustacea of the United States. Journal of the Academy of Natural Sciences of Philadelphia l(l-2):57-63, 65-80, , , [all 1817], , , , , , [all 1818]. Wicksten, M. K Pinnixa costaricana, a new species of crab from Central America (Brachyura: Pinnotheridae). Proceedings of the Biological Society of Washington 95: White, A Notes on four new genera of Crustacea. Annals and Magazine of Natural History 18(118): Zmarzly, D. L Taxonomic review of pea crabs in the genus Pinnixa (Decapoda: Brachyura: Pinnotheridae) occurring on the California shelf, with description of'two new species. Journal of Crustacean Biology 12: